Recent content by adamas

I am performing a nonlinear transient analysis in NX Nastran (SOL129) with geometric nonlinearities activated, but linear material. For this type of solution Nastran does not output element forces, but just stress/strain. My model consists mainly of CBEAM and I get in output a table where a...

I'll do the freebody check, thanks for the advice.

Yes, I have run a linear solution with the same applied loads and constraintes and here, as I expected, the SPC resultants are zero. The nonlinear analysis apparently converged, the tolerances EPSP and EPSW are below the threshold. Could the cause of this mismatching be the fact that the loads...

I have another question regarding the applied load (OLOAD) and SPC force resultants in SOL106. I am applying a balanced set of loads and, as expected, forces and moments resultants in OLOAD table are close to zero. Therefore I expected as well the SPC resultants to be zero, instead they are not...

I tried to increase the bending moment of inertia ratio (12I/T**3) in the PSHELL cards of the elements that were buckling and this improves the convergence, even though for the higher loads it is still a problem. There are some forces with a very high magnitude applied to a single grid, do you...

Thank you for the answers. Actually there are no contacts in the model. The nonlinearities are just geometric nonlinearities activated by PARAM LGDISP 1. I checked the F06 and the grids with negative MATRIX/FACTOR DIAGONAL RATIO. However it's not a specific area of the model, but these grids...

I am doing nonlinear static analyses with NX Nastran (SOL106) on a FE model of a wingbox made up of CQUAD4 and CBEAM elements. The loads are nodal forces and moments. The analysis is often not converging and I get this error message: *** USER INFORMATION MESSAGE 6194 (NCONVG) *** STOPPED...

Hello I have a Nastran model composed of CBAR elements and, since I have to run non linear analysis and apparently the CBAR formulation does not take into account geometric nonlinearities, I would like to convert all the CBAR to CBEAM automatically. Is there a way in Femap to do this? Thank you

Hi, I'm using NX 7.5 to perform kinematic simulations. I'm interested in the forces transmitted to each elements of the system. I can recover the forces and moments acting on the joints but not those acting on "coupler" elements, such as rack-pinion and cable couplers. Do you know if there is a...

I'm using sol 107 to extract the eigenvalues and eigenvectors of a FE model including damping. Among the methods available I've chosen complex Lanczos but I don't understand if the parameters SHIFTRj and SHIFTIj, which according to the manual are the real and imaginary part of the shift point...

So there isn't any way to overcome this error and use RBE3 indipendent grids in the A-SET for static condensation?

Hello, the error form the f06 is this one (where GRID 1 is the indipendent grid of the RBE3): *** USER FATAL MESSAGE 2101 (GP4) GRID POINT 1 COMPONENT 1 ILLEGALLY DEFINED IN SETS UM UBF *** USER FATAL MESSAGE 2101 (GP4) GRID POINT 1...

I would like to use static condensation (Guyan reduction) to calculate the normal modes of a wing box structure reduced to a set of grids along the main axis. These grids are connected to the structure through RBE3 (master grid) but doing like this NASTRAN gives a fatal error. Do you know if...

I have a 3D FEM model of a wing box structure made of CQUAD and CBEAM and I need to create an equivalent stick model using beam elements. Do you have any suggestion on how to do it? Is it possible to use Guyan reduction in Nastran to extract an equivalent stick representation? Thanks